Permanent magnet-embedded electric motor, compressor, and refrigerating and air-conditioning device

Abstract

An interior permanent magnet motor includes a stator and a rotor. The rotor includes a rotor core having a plurality of magnet receiving holes, and a plurality of permanent magnets are received in each of the magnet receiving holes. A plurality of slits are formed at a part between an outer peripheral surface of the rotor and an outer-side defining line of the each of the magnet receiving holes. At least one space portion is secured between the plurality of permanent magnets, and the space portion is opposed to any one of the plurality of slits in a direction parallel to a magnetic pole center line.

The invention claimed is: 
     
       1. An interior permanent magnet motor, comprising:
 a stator; and 
 a rotor rotatably arranged so as to be opposed to the stator, 
 wherein the rotor comprises a rotor core having a plurality of straight magnet receiving holes, 
 wherein a plurality of permanent magnets are received in each of the straight magnet receiving holes, 
 wherein a plurality of slits are formed in the rotor core at a part between an outer peripheral surface of the rotor and an outer-side defining line of the each of the straight magnet receiving holes, 
 wherein one or more space portions are formed between the plurality of permanent magnets in a state of being inserted into the each of the straight magnet receiving holes, and 
 wherein the one or more space portions are opposed to any one of the plurality of slits in a direction parallel to a magnetic pole center line, 
 wherein each of the straight magnet receiving holes include a pair of protruding portions formed on opposite ends of an inner-side defining line of a respective straight magnet receiving hole, and 
 wherein each of the straight magnet receiving holes includes a pair of recesses, which are recessed toward an inner side of the rotor in the radial direction, at portions on a magnetic pole center side in a circumferential direction with respect to the pair of protruding portions. 
 
     
     
       2. The interior permanent magnet motor according to  claim 1 , wherein,
 the plurality of permanent magnets include a first and second magnet, 
 the one or more space portions include a first space portion between the first and second magnets, 
 a circumferential width of the first space portion is represented by W 1 , 
 a circumferential width of the slit located at a position opposed to the space portion is represented by W 2 , and 
 a relationship of W 1 ≤W 2  is satisfied. 
 
     
     
       3. The interior permanent magnet motor according to  claim 1 ,
 wherein two of the permanent magnets are inserted into the each of the magnet receiving holes, and 
 wherein the two of the permanent magnets have the same size. 
 
     
     
       4. The interior permanent magnet motor according to  claim 1 ,
 wherein three of the plurality of permanent magnets are inserted into the each of the magnet receiving holes, and 
 wherein a circumferential width of each of the permanent magnets arranged on both end sides is smaller than a circumferential width of one of the three permanent magnets other than the permanent magnets arranged on both the end sides. 
 
     
     
       5. The interior permanent magnet motor according to  claim 4 , wherein coercivity of the each of the permanent magnets arranged on both the end sides is larger than coercivity of the one of the three permanent magnets other than the permanent magnets arranged on both the end sides. 
     
     
       6. The interior permanent magnet motor according to  claim 1 ,
 wherein four or more of the plurality of permanent magnets are inserted into the each of the magnet receiving holes, and 
 wherein a circumferential width of each of the permanent magnets arranged on both end sides is smaller than a circumferential width of each of two or more of the four or more permanent magnets other than the permanent magnets arranged on both the end sides. 
 
     
     
       7. The interior permanent magnet motor according to  claim 6 , wherein coercivity of the each of the permanent magnets arranged on both the end sides is larger than coercivity of the each of the two or more of the four or more permanent magnets other than the permanent magnets arranged on both the end sides. 
     
     
       8. A compressor, comprising, in an airtight container:
 a motor; and 
 a compression element, 
 wherein the motor comprises the interior permanent magnet motor of  claim 1 . 
 
     
     
       9. A refrigeration and air conditioning apparatus, comprising the compressor of  claim 8  as a component of a refrigeration cycle. 
     
     
       10. The interior permanent magnet motor according to  claim 1 , wherein
 the plurality of permanent magnets include first, second, and third magnets, 
 the one or more space portions include a first space portion between the first and second magnets and a second space portion between the second and third magnets, and 
 the plurality of slits includes a first slit opposed to the first space portion and a second slit opposed to the second space portion. 
 
     
     
       11. The interior permanent magnet motor according to  claim 10 , wherein
 a circumferential width of the first space portion is represented by W 1   a,    
 a circumferential width of the second space portion is represented by W 1   b,    
 a circumferential width of the first slit is represented by W 2   a,    
 a circumferential width of the second slit is represented by W 2   b,    
 a relationship of W 1   a ≤W 2   a  is satisfied, and 
 a relationship of W 1   b ≤W 2   b  is satisfied. 
 
     
     
       12. The interior permanent magnet motor according to  claim 1 , wherein
 the plurality of permanent magnets include first, second, third, and fourth magnets, 
 the one or more space portions include a first space portion between the first and second magnets, a second space portion between the second and third magnets, and a third space portion between the third and fourth magnets, and 
 the plurality of slits includes a first slit opposed to the first space portion, a second slit opposed to the second space portion, and a third slit portion opposed to the third space portion. 
 
     
     
       13. The interior permanent magnet motor according to  claim 12 , wherein
 a circumferential width of the first space portion is represented by W 1   a,    
 a circumferential width of the second space portion is represented by W 1   c,    
 a circumferential width of the third space portion is represented by W 1   b,    
 a circumferential width of the first slit is represented by W 2   a,    
 a circumferential width of the second slit is represented by W 2   c,    
 a circumferential width of the third slit is represented by W 2   b,    
 a relationship of W 1   a ≤W 2   a  is satisfied, 
 a relationship of W 1   b ≤W 2   b  is satisfied, and 
 a relationship of W 1   c ≤W 2   c  is satisfied.